Abstract: The invention generally provides for a network element and methods in the network element for allowing a matching entry in a forwarding memory to be found in a single search of the memory, for determining when an entry should be placed in the memory, and for determining when an entry should be removed from the memory, in order to make more efficient use of the fixed space available in the memory. The invention is particularly useful in making more efficient use of a Content Addressable Memory (CAM) for storing flow entries, and configuring the CAM to index an associated memory that stores forwarding and quality of service information for each CAM entry.

Abstract: A multi-layer network element for forwarding received packets from an input port to one or more output ports with quality of service. When output queues exceed or meet a threshold value below the queue's capacity packets are ramdomly discarded. When the queue becomes full, the network element determines which flow caused the queue to overflow. The priority of that flow is lowered. In a multicast packet, the packet may have different priorities at each output port. Scheduling of multiple output queues at each output port uses a weight round robin approach that allocates a weight portion of packets to transmit at each time interval. A packet is not interrupted during its transmission, even if the weight portion is met during a packet's transmission. The excess number of bytes transmited as a result of not interrupting the packet are accounted for in the next round.

Abstract: A multi-layer network element for forwarding received packets from an input port to one or more output ports. The packet is examined to look for first and second forwarding information. A packet is also assigned to a class and provided with default packet forwarding information. An associative memory is searched once for each type of information. The results from the two searches are combined with the default packet forwarding information to forward the packet to the appropriate one or more output ports. In some instances, the results of the first search dominate the forwarding decision, in other, the results of the second search dominate the forwarding decision, and in still other instances, the default information dominates.

Abstract: A multi-layer network element for forwarding received packets from an input port to one or more output ports. The packet is examined to look for different types of forwarding information. An associative memory is searched once for each type of information. The results from the two searches are combined to forward the packet to the appropriate one or more output ports. The packet may be examined for other information as well to make the forwarding decisions. In one embodiment, the invention examines the packet for layer 2 information as the first type and layer 3, and perhaps some layer 4, information as the second type. The results are merged to determine the most appropriate combination of layer 2 or layer 3 forwarding decisions for the packet.

Abstract: A method and apparatus for providing hardware-assisted CPU access to a forwarding database is described. According to one aspect of the present invention, a switch fabric provides access to a forwarding database on behalf of a processor. The switch fabric includes a memory access interface configured to arbitrate access to a forwarding database memory. The switch fabric also includes a search engine coupled to the memory access interface and to multiple input ports. The search engine is configured to schedule and perform accesses to the forwarding database memory and to transfer forwarding decisions retrieved therefrom to the input ports. The switch fabric further includes command execution logic that is configured to interface with the processor for performing forwarding database accesses requested by the processor.